The present invention pertains to methods for preparing aromatic polymers More particularly, the present invention pertains to processes for the preparation of poly(imide-amide)s. Poly(imides-amide)s are generally prepared by the reaction of 4-trimellitoyl anhydride chloride with an appropriate diamine as shown below. ##STR1##
In that procedure, an intermediate polyamic acid is cyclized in an imide forming step with the elimination of water. This procedure presents the shortcomings of using moisture sensitive acid chlorides and driving off a small molecule in the imide forming step, which can create voids and defects in the polymer product. Poly(imides-amide)s produced by this procedure have a backbone of alternating amide and imide units.
Japanese Kokai 123823, published May 16, 1 989, and Yoneyama et. al., Macromolecules, Vo. 21, 1988, pp. 1908-1911 disclose the use of a Heck carbonylation reaction, that is, a transition metal catalyzed carbonylation and coupling, in the preparation of low molecular weight polyamides. U.S. Pat. Nos. 4,933,419; 4,933,466 and U.S. Pat. No. 4,933,467 and U.S. Pat. No. 4,933,468 disclose methods which utilize Heck carbonylation reactions to produce esters, imides and imide-amides, respectively.
Amide formation from aryl and vinyl trifluoromethane sulfonates is reported in Ortar, et. al., Tetrahedron Letters, Vol. 26, (1985,pp. 1109-1112 pp. 3931-3934.